The reaction of 2-thiobarbituric acid with biologically active alpha,beta-unsaturated aldehydes.

The standard assay for lipid peroxidation is the measurement of the pink, 532 nm absorbing chromogen which is formed upon reaction of 2-thiobarbituric acid (TBA) with the lipid peroxidation product malonaldehyde (MDA). The present studies indicate that the toxic lipid peroxidation product trans-4-hydroxynonenal and its dehydration product trans,trans-nonadienal react with TBA to form chromogens which absorb maximally at 530 and 532 nm, respectively. Other biologically active alpha,beta-unsaturated aldehydes, such as acrolein and crotonaldehyde, short-chain homologs of alkenals formed during lipid peroxidation, and trans,trans-muconaldehyde, a novel diene dialdehyde, react with TBA to form products which absorb maximally at 495 nm. The molar extinction coefficients of the aldehyde:TBA chromogens formed were found to vary widely, suggesting that only small contributions to the 532 nm absorption by TBA adducts of reactive aldehydes other than MDA may be encountered during the use of the TBA assay.